植被恢复对侵蚀型红壤碳吸存及活性有机碳的影响

依托江西水土保持生态科技园,研究了侵蚀型红壤退化裸地恢复为百喜草地、柑橘果园和湿地松林后,0~100 cm深度范围内不同土层(0~10、>10~20、>20~40、>40~70和>70~100 cm)中w(TOC)(TOC为总有机碳)以及表层(0~40 cm)土壤中活性有机碳组分含量的变化. 结果表明:①退化裸地土壤中w(TOC)和有机碳库储量分别仅为4.73 g/kg和48.41 t/hm2,均处于较低水平,w(TOC)的垂直分布特征也不明显；恢复为百喜草地和柑橘园后,w(TOC)分别增至7.08和7.69 g/kg,有机碳库储量分别增至55.09和70.78 t/hm2,并且植被恢复对表层土壤中w(TOC)影响显著,而对深层(>40 cm)土壤影响有限. ②以退化裸地为对照,百喜草地和柑橘果园土壤碳吸存量分别为6.68和22.36 t/hm2,平均碳吸存速率分别为0.51和1.72 t/(hm2·a)；以保存较好的湿地松林为参照,退化裸地、百喜草地和柑橘果园土壤碳吸存潜力分别为23.71、17.03和1.34 t/hm2,说明严重侵蚀地的碳吸存潜力巨大. ③侵蚀型红壤退化裸地的植被恢复可积极促进表层土壤中DOC(水溶性有机碳)、MBC(微生物生物量碳)和POC(颗粒有机碳)的积累,同时该影响存在表聚效应,即植被恢复后土壤表层中活性有机碳组分含量在w(TOC)中所占比例增大. 

Effects of Vegetation Restoration on Soil Carbon Sequestration and Active Organic Carbon in Eroded Red Soil

Proper management and vegetation restoration can enhance the carbon sequestration of degraded soil and reduce atmospheric CO₂ concentration. The present study investigated the changes of soil total organic carbon (TOC, 0-10、>10-20、>20-40、>40-70 and >70-100 cm) pools and active organic carbon (0-40 cm) from eroded red bare land conversion to Paspalum notatum Flugge grassland as well as planting herbal citrus orchards and Pinus elliottii forest in Jiangxi eco-technology garden for soil and water conservation. The w(TOC) and pool were 4.73 g/kg and 48.41 t/hm2, which were not significantly different over the vertical distribution in the bare land, but obviously increased in the surface soil. After planting herbals and fruit industry, the w(TOC) values were 7.08 and 7.69 g/kg, and the soil carbon pools were 55.09 and 70.78 t/hm2, slightly affected under the depth of 20 cm. Compared to the bare land, the soil carbon sequestration amounts at 100 cm depth were 6.68 and 22.36 t/hm2, and the soil carbon sequestration rates were 0.51 and 1.72 t/(hm2·a) in grassland and citrus orchards. Compared to the P. elliottii forest, the soil carbon sequestration potentials were 23.71,7.03 and 1.34 t/hm2 respectively for the three lands. The restoration of degraded soil played an important role in increasing carbon sink because of higher carbon sequestering potential in degraded soil. Vegetation restoration in degraded red soil positively impacted the content of dissolved organic carbon, microbial biomass carbon and particulate organic carbon, especially making active carbon more aggregate to upper soil surface.